"It take a lot of time, it's tedious work so it would take someone looking out for you, making sure no one was coming around to check on you," said Detective Sergeant JJ Hamlet, Guilford County Sheriff's Office.

The units that were stolen weigh several hundred pounds each and Hamlet says they retail for about $1,400.

A doctor office's unit was stolen but a majority of the businesses targeted are currently vacant.

Hamlet says the crooks likely chose these businesses because they are empty. He says they probably thought they could go undetected until the business got rented out, or at least until the landlord came to check on the place.

The thieves skipped the Town and Country Barber Shop, but the salon's owner says what they did is bad enough.

"You just never expect anything in a neighborhood like this for something like that, a break-in as brazen as this. I can see one but they came in and took everybody's," explained Theresa Sanchez, owner, Town and County Barber Shop.

"It does make me worry," explained Sanchez. "If somebody would be brave enough to do that, they might be brave enough to walk in my door you know what I'm opened."

Hamlet says it's often difficult to track down the lost units because crooks sell them for scrap metal. It's not uncommon for thieves to steal items like this in one town, and try to sell it another, says Hamlet.

State laws help authorities track criminals like these that try to sell stolen good to scrap metal shops.

The shops are required to write down the name of the seller trying to get rid of metals like copper. In some cases, they must make a copy of the seller's driver's license and take a photograph or video of the seller with the metal.